I love TOS, but I understand your viewpoint. Were I new to the whole ball of wax I might feel the same way.
In its day, it was some of the most thoughtful television on the air. Hence its big following among college kids and high school nerd (lovingly meant) then.
Trying to be objective, TOS has a verve and energy that TNG lacks by design (GR's idea that the crew all get along). Later Trek has deliberately more complex stories (A/B plots) with more character development, I'll give ya that.
But many people feel as you, so I don't know if I'd really call TOS over-rated these days. Well-loved, for sure.
Thanks for the nice and thoughtful response. In retrospective, I probably should not have titled this thread "TOS- Overrated?", but rather "Do you enjoy the spin-off shows more than TOS?", or something along those lines. I don't think it was fair for me to call it overrated because it was a significant stepping stone in science fiction and it tackled a lot of controversial issues back in the day. For that alone I think it deserves its praise, even if it's not something I personally enjoy.